Rifling band



June I, 1948. I MCBRIDE 2,442,369

- RIFLING BAND Filed July 20, 1942 Edward. T-M1:E1ride Patented June 1, 1948 7 UNITED STATES 2,442369 mFLmGmAmi- Edward T. McBride, United States Army, Hawthorne, N. J., assignor *to United States of America as represented by the Secretary of War Application July 20, 1942, Serial No. 451,661

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) 2 Claims The invention described herein may be manuiactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to rifling bands for projectiles. Such bands have heretofore been made of solid copper cut from a length of tubing and pressed into an annular groove on the projectile. Thus much of the strategically valuable copper is a dead loss since much of it is not employed to engage the rifling in the gun bore.

It is therefore an object of the invention to provide a rifling band employing a minimum of the material required to engage the rifling. This object is accomplished by providing a filler for the tube, so that the filler takes up much or most of the space which would be occupied by the metal not employed to engage the rifling. The tube may be filled with any suitable plastic. It is then flattened, cut into lengths, and each length is formed into a torus by joining the ends. Alternatively, the groove in the projectile may be filled with a suitable plastic, and a layer of soft metal may be formed over the plastic, as by electroplating. Or, the soft metal may be electroplated onto a torus of plastic material, which is then fixed in place on the projectile.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 of the drawings shows a projectile pro vided with a rotating or rifling band made according to the invention. This view is shown with parts broken away and in section to bring out details.

Fig. 2 is a longitudinal section through a tube of soft metal filled with a plastic substance according to the invention,

Fig. 3 is a view in section on line 33 of Fig. 2.

Fig. 4 is a view of the tubing of Figs. 2 and 3 after torus.

Fig. 5 shows a modified application of the invention.

Shown in Fig. 1 is a riding or rotating band 2 on a projectile 4 which is provided with a circumferential groove 6 to receive the band. The band is made up of a tube 8 of a suitable soft metal such as one of the group comprised of copper, silver, gold, lead, tin, magnesium and aluminum. Or the metal may be taken from any of the groups 1, 2, 3 and 4 of the periodic table. It will of course be understood that the aboveflattening, cutting, and forming into an classified elements may be used singly or in combination as alloys. Soft iron may moreover be used, uncombined or as steel.

Where lead is used, either solid to make up the entire band or filled with a non-metallic center, it is suggested that the lead be alloyed with an element such as calcium or tellurium to form an age hardenable alloy, the hardening of which may be performed in the manner well known to those skilled in the art,

The metal tube described above is filled with a substance having the desired elasticity, preferably a thermoplastic such as cellulose acetate or cellulose acetate butyrate. This filling may be done in any of a number of ways. A preferred method is that of extruding the thermoplastic material I!) into a tube 8' substantially circular in cross-section, as shown in Fig. 3. The plastic filled tube is then flattened, as by rolling, to form the cross-section shown in Fig. 1. Alternatively, the tubing may be flattened before filling with plastic, if desired. After flattening, or after filling of a previously flattened tube, the tubing is cut into proper lengths for rifling bands, and each length is formed into a torus l2, as shown in Fig. 4. The ends may be welded together, as indicated at I4.

Ring or torus I2 is made large enough to slip over projectile 4, and is rolled or otherwise pressed into groove 6 in the same manner as the conventional rifling band.

Instead of by the method detailed above, ring 12 may if desired be made by electrodeposition of the selected soft metal upon a preformed torus or ring Of plastic. A ring l2 made in this manner would of course not have the joint I4 indicated in Fig. 4.

Still another application of the invention may be adopted, Fig. 5 shows a rifling band 2' on a projectile l. Band 2 is formed by filling groove 6 with a plastic substance l0, which may be the same as the substance l0 explained above, or any other suitable material. Plastic I0 is then coated over, by electrodeposition or other suitable means, with a layer of soft metal 8", which may be any suitable metal, such as copper or the like as set forth above in connection with the discussion of tubing 8.

I claim:

1. The method of making the rifiing band for a projectile comprising the steps of extruding a thermoplastic non-explosive cellulose ester into a metal tube substantially circular in cross-section, flattening the tube by rolling, cutting the flattened tube into sections of definite length.

bringing the ends of said section together over REFERENCES CITED zbz'zlszifiss szzisszalox iisiezz ztsiufiz g; or m liga projectile 01: a gun having a rifled bar- 5 N D STA S PATENTS ii ii1 fia lfiii i fefifii l$1311 2;gifi fifi g fj ff feg in and completely filling said channel, said band' 1 1:861:522 Brandt 1932 comprising a. hollow toroid of soft metal and, a .v

cellulose acetate plastic completely filling said. 10

toroid. 3

EDWARD T. MCBRIDE. 

